This invention relates to conditioning cylinders, and more particularly to conditioning cylinders having flights, backmixing baffles, gentler conditioning nozzles and air recirculation.
Conditioning cylinders having rows of pins fitted on their inside walls are currently used for blending, steam-conditioning, drying, and applying flavorants to tobacco or other similar materials. The conditioning cylinder is positioned with the entrance end elevated and is rotated about its longitudinal axis. A typical cylinder for conditioning tobacco is about 28 feet long, about 8 feet in diameter, inclined at an angle of about 21/2 degrees from horizontal, and rotated at about 13 revolutions per minute. Material to be processed enters the conditioning cylinder at the elevated end and the rotation mixes and conveys the material along the length of the cylinder, eventually discharging the material at the lower end.
Steam-conditioning tobacco involves increasing the moisture content in the tobacco from about 12% to 16.5%. This increase in moisture content is accomplished by spraying the tobacco in the conditioning cylinder with steam and water so that the tobacco absorbs this moisture. The increase in moisture content makes the tobacco leaves more pliable and less susceptible to breakage during subsequent processing operations required to manufacture tobacco cigarettes.
It is desirable to condition the tobacco with minimal material degradation and uniform moisture application.
A developed view of the interior of a conditioning cylinder 100 constructed in accordance with conventional principles and commercially available from Dickinson Corp., Winchester, England, is shown in FIG. 1. Cylinder pins 110 are used to convey and lift the tobacco during rotation of cylinder 100. However, the action of the pins often degrades the tobacco by breaking the tobacco into smaller pieces as it moves through the cylinder.
FIG. 4 shows a steam and water spray nozzle assembly 300 also commercially available from the Dickinson Corp. A closed recirculation duct system (not shown) recirculates air from the exit to the entrance. This design may not uniformly moisturize the tobacco and may raise the temperature of the tobacco to detrimental levels, also degrading the final product.
It will be appreciated from the foregoing, that an apparatus and method which uniformly conditions the material or tobacco, while reducing material degradation and maintaining the material at lower temperatures would be a needed improvement. The present invention fulfills this need.